image-size/dist/types/jxl.mjs

get dimensions of any image file

// lib/utils/bit-reader.ts
var BitReader = class {
  constructor(input, endianness) {
    this.input = input;
    this.endianness = endianness;
    // Skip the first 16 bits (2 bytes) of signature
    this.byteOffset = 2;
    this.bitOffset = 0;
  }
  /** Reads a specified number of bits, and move the offset */
  getBits(length = 1) {
    let result = 0;
    let bitsRead = 0;
    while (bitsRead < length) {
      if (this.byteOffset >= this.input.length) {
        throw new Error("Reached end of input");
      }
      const currentByte = this.input[this.byteOffset];
      const bitsLeft = 8 - this.bitOffset;
      const bitsToRead = Math.min(length - bitsRead, bitsLeft);
      if (this.endianness === "little-endian") {
        const mask = (1 << bitsToRead) - 1;
        const bits = currentByte >> this.bitOffset & mask;
        result |= bits << bitsRead;
      } else {
        const mask = (1 << bitsToRead) - 1 << 8 - this.bitOffset - bitsToRead;
        const bits = (currentByte & mask) >> 8 - this.bitOffset - bitsToRead;
        result = result << bitsToRead | bits;
      }
      bitsRead += bitsToRead;
      this.bitOffset += bitsToRead;
      if (this.bitOffset === 8) {
        this.byteOffset++;
        this.bitOffset = 0;
      }
    }
    return result;
  }
};

// lib/types/utils.ts
var decoder = new TextDecoder();
var toUTF8String = (input, start = 0, end = input.length) => decoder.decode(input.slice(start, end));
var toHexString = (input, start = 0, end = input.length) => input.slice(start, end).reduce((memo, i) => memo + `0${i.toString(16)}`.slice(-2), "");
var getView = (input, offset) => new DataView(input.buffer, input.byteOffset + offset);
var readUInt32BE = (input, offset = 0) => getView(input, offset).getUint32(0, false);
function readBox(input, offset) {
  if (input.length - offset < 4) return;
  const boxSize = readUInt32BE(input, offset);
  if (input.length - offset < boxSize) return;
  return {
    name: toUTF8String(input, 4 + offset, 8 + offset),
    offset,
    size: boxSize
  };
}
function findBox(input, boxName, currentOffset) {
  while (currentOffset < input.length) {
    const box = readBox(input, currentOffset);
    if (!box) break;
    if (box.name === boxName) return box;
    currentOffset += box.size > 0 ? box.size : 8;
  }
}

// lib/types/jxl-stream.ts
function calculateImageDimension(reader, isSmallImage) {
  if (isSmallImage) {
    return 8 * (1 + reader.getBits(5));
  }
  const sizeClass = reader.getBits(2);
  const extraBits = [9, 13, 18, 30][sizeClass];
  return 1 + reader.getBits(extraBits);
}
function calculateImageWidth(reader, isSmallImage, widthMode, height) {
  if (isSmallImage && widthMode === 0) {
    return 8 * (1 + reader.getBits(5));
  }
  if (widthMode === 0) {
    return calculateImageDimension(reader, false);
  }
  const aspectRatios = [1, 1.2, 4 / 3, 1.5, 16 / 9, 5 / 4, 2];
  return Math.floor(height * aspectRatios[widthMode - 1]);
}
var JXLStream = {
  validate: (input) => {
    return toHexString(input, 0, 2) === "ff0a";
  },
  calculate(input) {
    const reader = new BitReader(input, "little-endian");
    const isSmallImage = reader.getBits(1) === 1;
    const height = calculateImageDimension(reader, isSmallImage);
    const widthMode = reader.getBits(3);
    const width = calculateImageWidth(reader, isSmallImage, widthMode, height);
    return { width, height };
  }
};

// lib/types/jxl.ts
function extractCodestream(input) {
  const jxlcBox = findBox(input, "jxlc", 0);
  if (jxlcBox) {
    return input.slice(jxlcBox.offset + 8, jxlcBox.offset + jxlcBox.size);
  }
  const partialStreams = extractPartialStreams(input);
  if (partialStreams.length > 0) {
    return concatenateCodestreams(partialStreams);
  }
  return void 0;
}
function extractPartialStreams(input) {
  const partialStreams = [];
  let offset = 0;
  while (offset < input.length) {
    const jxlpBox = findBox(input, "jxlp", offset);
    if (!jxlpBox) break;
    partialStreams.push(
      input.slice(jxlpBox.offset + 12, jxlpBox.offset + jxlpBox.size)
    );
    offset = jxlpBox.offset + jxlpBox.size;
  }
  return partialStreams;
}
function concatenateCodestreams(partialCodestreams) {
  const totalLength = partialCodestreams.reduce(
    (acc, curr) => acc + curr.length,
    0
  );
  const codestream = new Uint8Array(totalLength);
  let position = 0;
  for (const partial of partialCodestreams) {
    codestream.set(partial, position);
    position += partial.length;
  }
  return codestream;
}
var JXL = {
  validate: (input) => {
    const boxType = toUTF8String(input, 4, 8);
    if (boxType !== "JXL ") return false;
    const ftypBox = findBox(input, "ftyp", 0);
    if (!ftypBox) return false;
    const brand = toUTF8String(input, ftypBox.offset + 8, ftypBox.offset + 12);
    return brand === "jxl ";
  },
  calculate(input) {
    const codestream = extractCodestream(input);
    if (codestream) return JXLStream.calculate(codestream);
    throw new Error("No codestream found in JXL container");
  }
};

export { JXL };